Chest
Volume 142, Issue 6, December 2012, Pages 1469-1473
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Original Research
Chest Infections
Reversed Halo Sign in Invasive Fungal Infections: Criteria for Differentiation From Organizing Pneumonia

https://doi.org/10.1378/chest.12-0114Get rights and content

Background

The purpose of this study was to identify CT scan findings that differentiate the reversed halo sign (RHS) caused by invasive fungal infection (IFI) from the RHS caused by organizing pneumonia (OP).

Methods

We retrospectively reviewed CT scans of patients with RHS caused by IFI or OP. The study included 15 patients with proven or probable IFI (eight men and seven women) and 25 patients with biopsy-proven OP (13 women and 12 men). The CT images were reviewed individually by two chest radiologists who were blinded to the final diagnosis.

Results

Reticulation inside the RHS was observed in 14 of the 15 patients with IFI (93%) and in no patient with OP. The maximal thickness of the consolidation rim was 2.04 ± 0.85 cm for IFI and 0.50 ± 0.22 cm for OP. Pleural effusion was noted in 11 of the 15 patients with IFI (73%) and in no patient with OP. Other parenchymal abnormalities, such as consolidation and ground-glass and linear opacities, were observed in both groups. The number of lesions showing the RHS did not differentiate IFI and OP.

Conclusion

The presence of reticulation inside the RHS, outer rim thickness > 1 cm, and associated pleural effusion strongly suggest the diagnosis of IFI rather than OP.

Section snippets

Materials and Methods

All participating institutions provided institutional review board approval for this study (MD Anderson Cancer Center Protocol ID No. PA12-0047, Universidade Federal do Rio de Janeiro-Comitê de Ética e Pesquisa–Protocolo No. 089/10; the other institutions waived the institutional review board), and the requirement for informed patient consent was waived. We retrospectively reviewed the CT scans and medical records of 15 patients with IFI (invasive pulmonary aspergillosis or zygomycosis) and 25

Results

A single lesion with the RHS was observed in 13 of 25 patients with OP (52%). More than one lesion with the RHS was noted in the remaining 12 patients (48%). Associated parenchymal abnormalities were detected in 12 patients (48%), characterized as consolidations, ground-glass opacities, and linear opacities. No patient presented with lymph node enlargement or pleural effusion. No RHS lesion in the OP group exhibited reticulation of its inner component. The average maximal thickness of the

Discussion

We found that the presence of a pleural effusion associated with the RHS and the morphologic characteristics of the RHS can help differentiate patients with IFI from those with OP. An effusion was present in 73% of patients with IFI and in no patient with OP. In patients with IFI, central reticulations of the RHS were common (93%), and the outer consolidation rim was thick (average, 2 cm); in contrast, no RHS central reticulation was observed in patients with OP, and the outer consolidation rim

Acknowledgments

Author contributions: Dr Marchiori was the principal investigator and is the guarantor of the entire manuscript.

Dr Marchiori: contributed to the coordination and design of the study, data interpretation, and revision of the manuscript.

Dr Marom: contributed to the high-resolution CT scan evaluation, literature review, and revision of the manuscript.

Dr Zanetti: contributed to the data interpretation, literature review, and revision of the manuscript.

Dr Hochhegger: contributed to the collection of

References (19)

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Funding/Support: The authors have reported to CHEST that no funding was received for this study.

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